Luke has 4 more than triples the number of model cars that Andrew has. Luke has 31 cars. How many cars does Andrew have? {Write and solve an equation}

Andrew has 9 cars

Step-by-step explanation:

Let's start by defining what our unknowns are and how to name them:

For the number of cars Andrew has: let's use the letter A

For the number of cars Luke has: let's use the letter L

Not write the first sentence in mathematical terms:

"Luke has 4 more than triples the number of cars that Andrew has."

L = 3 * A + 4

The second phrase results on a very simple equation since it just states the number of cars that Luke has:

L = 31

Now we can combine these two equations by replacing the variable "L" in the first equation with the second equation and then solve for A:

L = 3 * A + 4

31 = 3 * A + 4

31 - 4 = 3 * A

27 = 3 * A

A = 27/3

A = 9

Therefore, Andrew has 9 cars.